1. Field of the Invention
The present invention relates to a print control device, an inkjet recording apparatus, a print control method, and a printing system each for processing data for form overlay printing.
2. Description of the Related Art
In general, a nozzle shape varies among a plurality of nozzles included in a recording head provided in an inkjet recording apparatus due to a nozzle forming process. Such variation causes variation in an ink amount discharged from each nozzle, thereby causing print density unevenness.
In regard to the inkjet recording apparatus, there has been widely known a piezoelectric method that uses a piezoelectric element, and the like method, as well as a heater driving method in which a heater is provided in each nozzle and an ink is discharged by use of bubbles generated by selectively heating and boiling the ink. In the heater driving method, it is possible to control an ink amount to be discharged, by controlling a driving pulse width to drive the heater provided per nozzle. However, even if an ink discharge amount is adjustable by the method, it is actually difficult to completely cope with nonuniformity in output images. Further, in a case where the number of nozzles is extremely large, if driving pulse widths of all the nozzles are controlled individually, problems with an increase of a circuit scale and an increase of a manufacturing cost may be caused.
In view of this, head shading correction may be performed to correct a printed image. In general, the head shading correction is performed on a multiple-valued image signal (e.g., a CMYK signal) converted, per recording head of a printing device, from an RGB signal constituting an original image of the printed image. Japanese Patent Application Laid-Open No. 2003-231245 discloses a printing system constituted by a printing device and a PC terminal device and performing a head shading technique. Japanese Patent Application Laid-Open No. 2003-231245 discloses that in order to establish consistency between a plurality of pieces of characteristic information of nozzles constituting a recording head of the printing device, and that recording head of the printing device which is connected to a host PC, printing characteristic data peculiar to the recording head is written in a memory in the recording head.
In the meantime, there has known a printing technique called form overlay in order to create a printed material in which desired data is written with respect to a given format (form). In the form overlay, form data indicative of a form part is created in advance, external data such as values or text strings is incorporated (overlaid) in a predetermined place (a field graphic) of the form data, and an image is printed or displayed.
In general, the recording head is attachable and detachable in the printing device and may be replaced by a user. When the recording head is replaced, naturally, printing characteristic data peculiar to the recording head and to be used for head shading correction is also changed. When the printing characteristic data is changed from one at the time of creating the form data, the head shading correction is not performed appropriately at the time of form overlay printing, thereby causing print density unevenness.